Travel control for a gas spring and gas spring having very short travel modes

ABSTRACT

A gas spring capable of having long and short travel modes is described. The gas spring uses liquid in combination with pressurized air to affect the travel length. Unlike conventional gas springs, the gas spring according to the invention may have its travel reduced more than, for example, by 50%.

RELATED PATENT APPLICATIONS

This application is related to our co-pending US Patent Applications:

a) Ser. No. 10/237,333, filed Sep. 5, 2005, published as US Pub.2003/0234144 (the “'144 application”) on Dec. 25, 2003, and entitled “Onthe Fly Adjustable Gas Spring”;

b) Ser. No. 11/372,707, filed Mar. 10, 2006, and entitled “Gas Springand Travel Control For Same and Method”; and

c) Ser. No. 11/560,403, filed Nov. 16, 2006, and entitled “Gas SpringCurve Control In An Adjustable-Volume Gas-Pressurized Device” (the '403application).

All patents and patent applications referred to herein are incorporatedby reference into this patent application.

FIELD OF THE INVENTION

The current invention is generally directed to improvements useful ingas-spring devices employed in, for example, two-wheeled vehiclesuspension elements such as: shock absorbers, suspension forks and othervariable-volume gas-pressurized devices (“gas springs”).

BACKGROUND OF THE INVENTION Introduction

As described in detail in the '144 application and summarized in the'403 application, the stiffness (force-versus-travel or, as used herein,“spring curve”) of a gas spring may be associated with “travel modes”(e.g. long and short). For example, as depicted in the two spring curvesof FIG. 15 of the '144 application and described in para

of the '144 application, travel modes are indicative of how far a springcompresses when subjected to a given compression force (i.e., a gasspring will compress more in long travel mode than in short travelmode). For example, for the gas spring described in the '144application, in the long travel mode (FIG. 13), the amount of travelproduced by a 750 pound force is approximately 1.75″. In the shorttravel mode (FIG. 14), the amount of travel produced by the same forceis approximately 1.27″. Note that for the reasons described in para[0063] of the '144 application, all pressure values are closeapproximations and effected by the presence of the negative gas spring.

In the '144 application, selection between the long and short travelmodes is easily accomplished on the fly by a rider making a small (e.g.¼) turn of an adjustment knob and without all the disadvantages of priorart methods for changing travel length (see discussion of prior art inthe '403 application). In the '144 application there are two gaschambers. The long travel mode is operative when the two gas chambersare in fluid communication with each other. The short travel mode isoperative when the two gas chambers are not in fluid communication witheach other.

Although the gas spring as shown in the '144 application is capable ofproducing two available travel modes, it is often desirable to have morethan two available travel modes—as described in the '403 application.Furthermore, it may often be desirable for the short travel mode toproduce a substantially shorter travel length than has been so farprovided such that for a given force, the distance between the travellimits of the long and short travel modes are spaced further apart,e.g., approximately 50% or more, or in other words, the travel in theshort travel mode is approximately 50% or less of the travel in the longtravel mode.

Finally, in general, by providing a rider with the ability to controlsuspension travel, riders have a tool for controlling the stiffness ofthe gas spring and the magnitude of the force that would cause a harshbottom-out and uncomfortable metal-to-metal contact. Furthermore, byproviding rider with a wide range of travel mode options, the suspensioncan, for example, be optimized for: (a) more consistent tire contactpatch (lower gas spring stiffness); (b) more comfortable ride (lower gasspring stiffness); (c) increased pedal efficiency (reduced pedal bob)(stiffer gas spring); and (d) reduced fore-aft pitching (stiffer gasspring).

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Due to the extensive use of schematic drawings herein, referencenumerals have not always been repeated from FIG to FIG when notnecessary to an understanding of the FIG or the invention. Furthermore,throughout the FIGs, cross-hatching density is used to symbolicallyrepresent relative gas pressures (see FIG. 1A). Therefore, an areacontaining less dense cross-hatching has a lower gas pressure than anarea having denser cross-hatching. Generally, cross-hatching ofstructural components has been minimized to minimize confusion withsymbolized “pressure cross-hatching”.

Additionally:

a) as in the '403 application, filled circles represent closed valvesand empty circles represent open valves; and

b) where possible, reference numerals from the '403 application havebeen used herein.

FIG. 1A depicts the relationships between representative exemplarypressures and their corresponding cross-hatching density.

FIG. 1B schematically depicts the gas spring of the '144 applicationmodified according to a first exemplary embodiment of the currentinvention and at full expansion.

FIG. 2A-2C schematically depict the operation of the modified gas springof FIG. 1B at different positions in the stroke, when in long travelmode.

FIG. 3A-3B schematically depict the operation of the modified gas springof FIG. 1B at different positions in the stroke, when in short travelmode.

FIG. 4A depicts the long travel and short travel spring curves producedby the modified gas spring of FIG. 1B in a manner similar to the springcurves depicted in FIG. 15 of the '144 application.

FIGS. 4B, 4C, 4D depict the different long and short travel spring curvecombinations that may be produced by the modified gas spring of FIG. 1Bwhen the amount of liquid in the gas spring is varied.

FIG. 4E compares the different long travel spring curves that may beproduced by the modified gas spring of FIG. 1B when the amount of liquidin the gas spring is varied.

FIG. 4F compares the different short travel spring curves that may beproduced by the modified gas spring of FIG. 1B when the amount of liquidin the gas spring is varied.

FIG. 5A-5D depict how the amount of liquid within the gas spring can bechanged to alter the short travel mode (all shown at full expansion).

FIG. 6 schematically depicts an alternative exemplary embodiment of amodified gas spring according to the invention, at full extension, andhaving two auxiliary chambers.

FIG. 7A-D depict the gas spring of FIG. 6 in each of the four travelmodes, respectively, and at their respective travel positions whensubjected to the same maximum pressure.

FIG. 8 is a graph depicting the spring curves produced in each of thefour travel mode settings of FIGS. 7A-D.

FIGS. 9A-F are different views of an exemplary physical embodiment of agas spring control valve according to the invention, as modified from anexemplary embodiment of the '403 application.

FIGS. 10A-D depict the gas spring control valve of FIGS. 9A-F in itsvarious operative settings.

FIGS. 11A-B depict another exemplary physical embodiment of a gas springcontrol valve according to the invention.

FIGS. 12A-D depict the gas spring control valve of FIGS. 11A-B in itsvarious operative settings.

FIG. 13 depicts another exemplary physical embodiment of a gas springcontrol valve according to the invention.

FIGS. 14A-C depict the modified gas spring control valve of FIG. 13 inits various operative settings.

FIG. 15 depicts a basic partial schematic layout of an exemplaryembodiment of the invention including an exemplary negative gas spring.

DETAILED DESCRIPTION OF THE INVENTION Basic Structure of an ExemplaryEmbodiment of the Invention

FIG. 1B schematically depicts the gas spring of the '144 applicationmodified according to an exemplary embodiment of the current invention,at full extension, and without a negative gas spring. While in manyinstances it may be advantageous to have a negative gas spring and oneskilled in the art would be aware that a negative air spring can be usedwith the exemplary embodiments of the present invention, for purposes ofsimplifying the bulk of the current discussion and its associatedcalculations, the negative gas spring and its associated effects havebeen omitted. However, FIG. 15 (discussed later) depicts a basic partialschematic layout of an exemplary embodiment of the invention includingan exemplary negative gas spring.

As schematically shown in FIG. 1B, gas spring 5 includes a gas springhousing 10 enclosing a main chamber C and one auxiliary chamber A1. Mainchamber C is defined as the volume between partition 35 and piston 12 atfull expansion. Auxiliary chamber A1 is defined as the volume betweenpartition 35 and the upper end 11 of gas spring housing 10. Thus, thetwo chambers may be separated from each other by partition 35, whichitself may have a valve 20. Valve 20 allows the user to selectivelyplace the two chambers in fluid communication using a controller, suchas a knob 67 positioned externally of the gas spring housing 10 andpreferably within the easy reach of a mounted rider for easy on-the-flymanipulation. Gas spring housing 10 may be a portion of a suspensionelement, such as a shock absorber, suspension fork leg, or other damper.Furthermore, when the piston 12 is fully retracted, a volume of liquidL, such as oil or any other fluid that will not degrade internal seals,etc., is added to partially fill main chamber C. Liquid L sits on piston12, which itself is supported by piston shaft 13. For the purposes ofthe upcoming basic exemplary embodiment of the invention, it is assumedthat the volume of liquid L fills approximately ⅓ the volume of mainchamber C. Liquid L may be added during manufacture of the gas spring 5and subject to routine maintenance only, or to change the travel modetravel limits as will be described below-need not be bothered with bythe rider. This is different from, for example, related art damperdesigns, such as extensively discussed in the '403 application, whichrequire the user to change the liquid level or the position of aninternal component each time the rider wants to change the gas springcurve. Finally, gas spring 5 is sealed and pressurized through aconventional pressurization valve S (see FIGS. 9A-9B) with a gas G (seedescription of pressurization in the '403 application) such that the gaspressures in main chamber C and auxiliary chamber A1 are equal.

Schematic Depiction of Long Travel Mode Operation

FIG. 2A-2C depict the modified gas spring according to this firstexemplary embodiment of the invention and operating in long travel mode.

First, as described in the '144 and '403 applications, in the longtravel mode, valve 20 is placed in its open position so that mainchamber C and auxiliary chamber A1 are in fluid communication with eachother. As previously mentioned, the gas pressures in main chamber C andauxiliary chamber A1 are equal.

In FIG. 2A, the gas spring 5 has begun to compress through its travel(note distance between piston 12 and piston stops 14). The liquid L iscarried by the inwardly moving piston 12 and as the volume of gas G inthe communicating main chamber C and auxiliary chamber A1 decreases, thegas pressure within communicating gas chambers C and A1 increases.

In FIG. 2B, the spring has compressed through its travel to a pointwhere the volume between the piston 12 and partition 35 was no longerable to contain the full volume of liquid L. Therefore, a portion of theliquid L passed through open valve 20 and into auxiliary chamber A1. Atthis point, all the gas that was previously between the piston 12 andpartition 35 has been displaced into auxiliary chamber A1 and thepressure of the gas has further increased as symbolized by the densercross-hatching of FIG. 2B.

Finally, if gas spring 5 is constructed according to the parameters ofTABLE ONE, as shown in FIG. 2C, the volume between the piston 12 andpartition 35 will decrease to substantially zero (size exaggerated forclarity and to symbolize the lack of metal-to-metal contact) and all thegas and substantially all the liquid that were between the piston 12 andpartition 35 will be in auxiliary chamber A1 (accordingly, the volume ofthe auxiliary chamber should be equal to or greater than the volume ofthe liquid to allow full travel in long travel mode). The pressure ofthe gas, of course, has increased as symbolized by the densercross-hatching of FIG. 2C relative to FIG. 2A and 2B.

Schematic Depiction of Short Travel Mode Operation

FIGS. 3A and 3B are discussed next. Note that in these figures—incontrast to FIGS. 2A-C—valve 20 is in its closed position (expressedagain by filled in circles). With valve 20 closed, the gas spring 5 isin the short travel mode because main chamber C and auxiliary chamber A1are not in fluid communication with each other.

As shown in FIG. 3A, the gas spring 5 has begun to compress through itstravel (note distance between piston 12 and piston stops 14). The liquidL is carried by the inwardly moving piston 12 and as the volume of thegas between the piston 12 and partition 35 decreases, the pressure ofthe gas G between the piston 12 and partition 35 increases. However,because valve 20 is closed, the gas pressure in auxiliary chamber A1remains constant and is irrelevant to this mode of operation. Thus, thehatching of the gas G between the piston 12 and partition 35 is denserthan the hatching of the gas in auxiliary chamber A1.

FIG. 3B depicts how, at some point during the compression stroke, theincreased pressure of gas G between the piston 12 and partition 35 willreach a value that precludes substantially any additional compression.As described below and generally depicted by FIG. 3B, the gas spring 5may be designed so that the point at which substantially no additionalcompression occurs can be approximately 50% of full travel.

Graphical Depiction of Short and Long Travel Operation

The spring curves of FIG. 4A illustrate the spring curves produced bythe gas spring 5 of FIG. 1B in each of its two different selectablemodes: the short-travel mode and the long-travel mode. The spring curvesof FIG. 4A result from the following initial gas spring conditions:

TABLE ONE Initial Gas Spring Conditions (piston at full expansion)Volume of main chamber C = 6 units. Volume of auxiliary chamber A1 = 4units. Volume of liquid in the main chamber ≈ ⅓ volume of the mainchamber (i.e. 2 units). Therefore, at full extension, liquid and gasfill the main chamber. Maximum Available Stroke = 6 units. Piston area =1 square unit. Initial Internal Gas Pressure = 100 PSI NOTE: One skilledin the art would recognize that units should come from a singleconsistent system of measurement.

As depicted by the long travel mode spring curve of FIG. 4A, the forceproduced by the gas spring as exemplified by FIGS. 2A-2C rises somewhatgradually and reaches, in this example, a value of 400 pounds at astroke distance of about 6 inches (i.e., full travel) (FIG. 2B). Asdepicted by the short-travel mode spring curve of FIG. 4A, the forceproduced by the gas spring as exemplified by FIGS. 3A-3B rises morerapidly and reaches, in this example, a value of 400 pounds at a strokedistance of about 3 inches (i.e., half travel )(FIG. 3B).

As those skilled in the art will recognize, these exemplary force andstroke values are based on, for example, the parameters of TABLE ONE.However, as those skilled in the art will recognize, a theoreticallyinfinite number of combinations of areas and pressures can produce theforce values in this example.

Modified Short Travel Modes

FIGS. 4B, 4C, and 4D depicts the complementary long and short travel gasspring curves produced by the exemplary embodiments of FIGS. 5B-D,respectively. The complementary long and short travel gas spring curvesproduced by the exemplary embodiment of FIG. 5A is shown in FIG. 4A. Ina two travel mode gas spring, such as described with references to FIGS.1B, 2A-2C, 3A-3B and 5A-5D, the gas spring 5 would be provided with onevalve setting for long travel and one valve setting for one of, forexample, “basic” short, “ultra-short” or “very-short”, or “substantiallyno short” travel.

Alternative short travel modes, such as very-short, ultra-short, andsubstantially no short travel may be easily produced by varying theamount of liquid L in the main chamber C as summarized in TABLE TWO,when all the other initial gas spring conditions described in TABLE ONEare kept constant:

TABLE TWO Volume of Oil at Full Short Travel Mode FIG Expansion BasicShort 4A, 5A ⅓C (2 units) Very Short 4B, 5B ⅔C (4 units) Ultra-Short 4C,5C ⅚C (5 units) Substantially No Short 4D, 5D .9C (5.4 units) TravelAs can be seen in FIGS. 4E, 4F, increasing the volume of the liquid inmain chamber C from ⅓ the fully expanded volume of main chamber C to 0.9the volume of main chamber C causes the short and long travels of gasspring 5 to decrease significantly. As these travels decrease, the forceproduced by the gas spring 5 rises from rapidly (basic short travel) toextremely rapidly (substantially no-short travel).

Alternative Embodiment

While the '144 application and the previously described exemplaryembodiment of the invention use one main and one auxiliary chamber toprovide two travel settings, i.e., long and short travel modes, the '403application uses one main and two auxiliary chambers to provide fourdiscrete travel mode settings. The user may select from among thevarious available settings on-the-fly, for example, by manipulating acontroller. According to the current invention, and using the teachingsof the '403 application, four user selectable travel mode settings mayalso be provided in an alternative exemplary embodiment of the currentinvention. Therefore, for example, FIG. 6 depicts a schematic version ofa fully expanded gas spring according to an exemplary alternativeembodiment of the invention applying the teachings of the '403application.

In particular, the gas spring is provided with a first auxiliary chamberA1 defined between partition 35 a and partition 35 b and a secondauxiliary chamber defined between partition 35 b and upper end 11 of thegas spring housing. Furthermore, auxiliary chambers A1, A2 may beselectively placed into fluid communication with main chamber C usingcontroller 67 to adjust the settings of valves 20 a, 20 b. While in the'403 application, only gas is displaced among the various gas chamberswhen they are in fluid communication, according to this alternativeexemplary embodiment of the invention, both gas and liquid may bedisplaced among the various gas chambers depending upon the settings ofvalves 20 a, 20 b. Note that as FIG. 6 is a schematic, valves 20 a, 20b, may take any form and even be part of a single valve assembly (seee.g. FIG. 11A-B, 12A-D, 13, 14A-C, where a single rotary disk valve isshown).

FIG. 7A-D schematically depict the operation of the gas spring accordingto this alternative exemplary alternative embodiment of the invention:

a) with the design parameters described in TABLE THREE, below;

b) in each of its four travel mode settings, respectively, as will bedescribed below; and

c) at the point in the travel of piston 12 where the pressure of the gasacting on the face of the piston 12 has increased to the same level(e.g. 400 psi) in each setting.

In particular:

(Long travel mode—FIG. 7A)—Valves 20 a and 20 b are open and theinwardly moving piston 12 displaces all the liquid L and all the gas Gthat were in the main chamber C into the first and second auxiliarychambers A1, A2 to the point where the pressure of the gas increases toabout 400 psi. In this exemplary embodiment, this occurs at, full travel(distance between piston 12 and partition 35 exaggerated for detail andto symbolize lack of metal-to-metal contact); and

(Medium travel mode—FIG. 7B)—Valve 20 b is open and valve 20 a is closedand the inwardly moving piston displaces all the gas G and some of theliquid L that were in the main chamber C into the second auxiliarychamber A2 until the pressure of the gas increases to about 400 psi; and

(Short travel mode—FIG. 7C)—Valve 20 a is open and valve 20 b is closedand the inwardly moving piston displaces all the gas G and some of theliquid L that were in the main chamber C into the first auxiliarychamber A1 until the pressure of the gas increases to about 400 psi; and

(Very short Travel mode—FIG. 7D) Valves 20 a and 20 b are closed and theinwardly moving piston compresses the gas G in the main chamber C untilthe pressure of the gas G in the main chamber C increases to about 400psi.

FIG. 8 depicts an exemplary family of gas curves that may correspond tothe long, medium, short, and very short travel modes summarizedimmediately above. As can be seen in FIG. 8, as the setting of the gasspring 5 changes from long travel mode to very short travel mode, thetravel produced by a given force decreases. The operation of thisexemplary embodiment when subjected to a 400 pound force in each travelsetting is summarized in TABLE THREE below.

TABLE THREE Exemplary Travel Controller Travel Valve Chambers PositionResulting From FIG. Setting Mode Valve 20a 20b Used a 400 pound Force 7A1 Long Open Open C, A1, A2 T 7B 2 Medium Closed Open C, A2 .81T 7C 3Short Open Closed C, A1 .69T 7D 4 Very Closed Closed C  .5T ShortAssumptions at Full Expansion: Volume main chamber C = 6 Volume firstauxiliary chamber A1 = 1.5 Volume second auxiliary chamber A2 = 2.5Volume of liquid L = 2 Travel = T = 6 units Initial Internal pressure =100 PSI Piston Diameter = 1 square unit. (see note re: units in TABLETWO above)

Exemplary Physical Embodiment

FIGS. 9A-F depict various views of an exemplary physical embodiment ofvalving that may be used with the gas spring 5 previously schematicallyshown in FIG. 6 (i.e., having two auxiliary chambers). This exemplaryphysical embodiment is generally similar to the gas spring control valvedescribed in the '403 application and therefore reference should be madeto that application for detailed structural and operationaldescriptions.

The major differences between the current exemplary physical embodimentand that of FIGS. 2-10 of the '403 application concerns modificationsneeded to allow liquid to flow with minimal restriction through thevarious flow ports that were previously designed only to accommodate gasflow. In the '403 application, where only gas was used, flow ports 40,45 had an exemplary diameter on the order of 0.050″ when unrestrictedgas flow between the various gas chambers was desired.

In the current invention, however, liquid and gas must be able to flowthrough the flow ports 40, 45 at a rate commensurate with potentiallylarge stroke velocities.

To achieve these large liquid flow capabilities, the gas spring controlvalve of FIGS. 2-10 of the '403 application may be modified in any waythat allows increased liquid flow rates.

For example, the cross-sections of flow ports 40, 45 may besignificantly increased. By increasing, for example, the cross-sectionfrom 0.050” ('403 application) to 0.187″ (current exemplary embodiment),flow area increases by a factor of about 14 times.

To accommodate these larger flow ports 40, 45, body portion 25 may needto be modified. For example, a body portion extension 25 e may beprovided between first end 25 a of body portion 25 and partition 35. Thewidth of extension 25 e is only slightly larger than the flow portdiameters. Additionally, to further contribute to reduced pressure dropswhile accommodating the larger fluid flows, instead of there being onlyone of each flow port 40, 45, according to an exemplary embodiment ofthe invention, there may two of each flow port. This allows greater flowvolumes and lower pressure drops. Accordingly, there may be a pair offirst ball valves 50 a and a pair of second ball valves 50 b (FIGS. 9C,9E).

FIGS. 10A-D depict the operation of the control valve in a similarmanner as described in the '403 application. In particular, the valveproduces four different valve settings that may produce the fourdifferent travel modes, as described above and in the '403 application.

Alternative Exemplary Physical Embodiment

As shown in FIGS. 15-16 of the '403 application, gas spring curvecontrol valve 20 may comprise a rotary disc valve rather than ballvalves. Reference should be made to the '403 application for a completedescription of the structure and operation of the rotary disc valve. Asshown in FIGS. 11A-14C herein, the rotary disc valves of the '403application may also be applied to the current invention and indifferent configurations.

For example, in FIGS. 11A-11B, herein, the structure of FIGS. 15-16 ofthe '403 application is shown—with the modification that the diametersof flow ports 40, 45 are made larger for the reasons previouslydescribed above. As in the '403 application, four different valvesettings are provided that are 45 degrees apart (FIGS. 11A-D).

In FIGS. 13, 14A-C, a compromise is made between the number of differentvalve settings and the capacity for liquid flow (i.e., liquid flowrate). Specifically, one of the four different valve settings and itsassociated travel mode are eliminated. As an example, the travel modesetting that may be removed could be the one where the main chamber andthe first auxiliary (lower) chamber are in fluid communication. Theelimination of the valve setting opens up additional angular space onbody 25 so flow ports 40, 45 may be made oblong, or “kidney-shaped”(FIG. 13-14). The oblong flow ports 40, 45 provide for approximately 50%more flow rate than the related circular flow ports. Therefore, if adesigner is designing a gas spring that may be regularly subjected tolarger impacts, this embodiment of the present invention offers thedesign option of eliminating one of the travel settings in favor ofoblong ports to accommodate larger fluid flows.

Negative Gas Spring

FIG. 15 depicts an exemplary embodiment of the invention including anexemplary negative gas spring N that biases the gas spring towards thecompressed position. The negative gas spring may be applied to any ofthe previously described exemplary embodiments of the invention. The useof negative gas springs is generally described in, for example, U.S.Pat. No. 6,135,434 (Marking); U.S. Pat. No. 6,311,962 (Marking); U.S.Pat. No. 6,360,857 (Fox); and U.S. Pat. No. 6,105,988 (Turner).

According to the exemplary embodiment of FIG. 15, piston stop 14 may bemade into an annular piston stop disk 14′. Piston rod 13 may freelytranslate through the bore in the annular piston disk 14′, but thesurface of the piston rod is sealed against the annular piston stop disk14′, such as by use of an o-ring 15. Finally, a pressurized gas N′ maybe inserted into the spring chamber 68 defined between piston bottom 12′and a top surface 14a of annular piston stop disk 14′. The gas may beinserted into spring chamber 68 using, for example, a conventional gasvalve 69 (shown schematically) in combination with a gas port 70 inpiston rod 13. One skilled in the art, using, for example, the teachingsof the patents mentioned immediately above in combination with theexemplary pressures mentioned throughout the present application wouldthen be able to determine the pressure of gas N′ to tune the overall gasspring 5 to a desired performance.

Conclusion

While the invention has been described with respect to certain exemplaryembodiments, the scope of the invention shall only be limited by theappended claims.

LIST OF REFERENCE NUMERAL USED

5, 5′ gas spring 10 gas spring housing 11 upper end of gas springhousing 12 piston 12′ piston bottom 13 piston shaft 14 piston stop 14′annular piston stop disk 14a top of annular piston stop disk 15 seal 20,20a, 20b control valve 25 body portion 25a first end of body portion 25ebody portion extension 35, 35a, 35b partition 40 first flow port 45second flow port 50 ball valve 67 knob 68 negative gas spring chamber 69gas valve 70 gas port A1, A2 auxiliary chambers C main chamber G gas Lliquid N negative gas spring N′ negative gas spring gas

1. A gas spring for a two-wheeled vehicle, comprising: a main chamberand at least one auxiliary chamber; a control valve for controllingwhether the main chamber and the at least one auxiliary chamber are influid communication with each other; a volume of liquid filling aportion of the main chamber at full expansion; pressurized gas fillingthe at least one auxiliary chamber and the remaining portion of the mainchamber; a movable piston for compressing the gas in the main chamberand displacing the liquid during a compression stroke of the gas spring.2. The gas spring of claim 1, wherein during a compression stroke andwhen the control valve is allowing fluid communication between the mainchamber and the at least one auxiliary chamber, substantially all thegas in the main chamber may be displaced into the at least one auxiliarychamber.
 3. The gas spring of claim 2, wherein after substantially allthe gas in the main chamber is displaced into the at least one auxiliarychamber, the piston may displace at least a portion of the liquid in themain chamber through the control valve and into the at least oneauxiliary chamber.
 4. The gas spring of claim 1, wherein at least duringsome portions of the compression stroke, liquid is not displaced fromthe main chamber to the at least one auxiliary chamber.
 5. The gasspring of claim 2, wherein during a compression stroke and when thecontrol valve is allowing fluid communication between the main chamberand the at least one auxiliary chamber, the piston displacessubstantially all the liquid in the main chamber through the controlvalve and from the main chamber to the auxiliary chamber.
 6. The gasspring of claim 1, wherein the at least one auxiliary chamber includesat least two differently sized auxiliary chambers and the control valveincludes a plurality of discrete settings for controlling whetherdifferent combinations of the main chamber, first auxiliary chamber andsecond auxiliary chamber are in fluid communication with each other. 7.The gas spring of claim 1, wherein when the control valve is notallowing fluid communication between the main and auxiliary chambers,the maximum piston travel is approximately 50% or less of the fulltravel.
 8. The gas spring of claim 1, wherein the user may select thesetting of the control valve using a controller positioned externally ofthe gas spring.
 9. The gas spring of claim 8, wherein the controllerincludes a knob.
 10. The gas spring of claim 1, including a housingforming at least a portion of a suspension element.
 11. A method ofproviding a gas spring with at least long and short travel modes,comprising the steps of: providing a gas spring housing with at leasttwo chambers; providing a control valve at least partially within thegas spring housing for controlling whether the at least two chambers influid communication with each other; partially filling at least one ofthe chambers with a liquid; filling the other chamber and the emptyportion of the chamber filled with oil with a pressurized gas; wherein:a) when the short travel mode is desired, the control valve is set tosubstantially inhibit fluid communication between the two chambers; andb) when the long travel mode is desired, the control valve is set toallow fluid communication between the two chambers and duringcompression of the gas spring at least a portion of the gas that is inthe chamber that also contains the liquid is displaced to the otherchamber.
 12. The method of claim 11, wherein when the gas spring is inlong travel mode, during compression of the gas spring at least aportion of the liquid is displaced from one chamber to the other. 13.The method of claim 11, wherein the short travel mode can be made evenshorter by increasing the amount of liquid in the chamber at leastpartially filled with liquid.
 14. The method of claim 11, wherein theshort travel mode provides a stroke of approximately 50% or less of thefull travel mode.
 15. The method of claim 11, wherein enough liquid isadded to the chamber at least partially filled with liquid that theshort travel mode provides a stroke of 50% or less of the full travelmode.
 16. A suspension element for a two-wheeled vehicle, comprising: amain chamber and at least one auxiliary chamber; a control valve forcontrolling whether the main chamber and the at least one auxiliarychamber are in fluid communication with each other; a volume of liquidfilling at least a portion of the main chamber; pressurized gas fillingthe at least one auxiliary chamber and the remainder of the mainchamber; a movable piston for compressing the gas in the main chamberand displacing the liquid during a compression stroke of the gas springwherein when the piston is at full expansion, the main chamber is atleast partially filled with pressurized gas.